There are a few things about PS:T that have yet to be surpassed, and none of them have to do with expensive stuff like graphics and voice acting or minute mechanical details like camera perspective, party size or D&D 2e combat.
What made PS:T good was that the vast majority of sidequests are of direct relevance to the principle characters both narratively and mechanically. Rather than rolling us through a giant cast of one-off RPG stereotype characters (plus one 'companion quest' per ally as per the Bioware model), each serves to deepen the characters we actually care about. We learn more of their past; we learn about their attributes and tendencies; we gain abilities for them that tie thematically to who they are. Only in PS:T do you get to recover one of your former eyes, stick it back inside your body, and in so doing gain both memories and abilities pertinent to those memories (and pertinent to you! Not to god damn Grimsby the Uninteresting who runs the inn and lost his paperwork in the wolf cave).
I've always been surprised that nobody else has done these things since. The stories we see in RPGs today are scattershot, unfocused, thematically oblivious, often lacking in good drama and tension. PS:T was directed, focused, thematically aware and for this reason it was filled to the brim with interesting things. I played through it again last summer; practically everyone you meet and everything you do is concerned with the parable of Nameless One, his past and of course his nature. Storytelling that looks inward rather than outward.
This, IMO, is what Obsidian games do best, you seem to be among the only ones in the entire game industry who can do it, and you should continue to do that because that's what makes your games special (regardless of how they fare on Metacritic).